Burj Khalifa

Burj Khalifa (Arabic: برج خليفة‎, "Khalifa Tower") is a very tall skyscraper in Dubai, United Arab Emirates and is the tallest building ever built, at 828 metres (2,717 feet). Before the building opened, it was called Burj Dubai. The building is 162 stories high. Construction of the tower was started in 2004. The building was officially opened on 4 January 2010.[2][3] It is the tallest structure made by humans in the world. The building is more than 300 metres (980 feet) taller than Taipei 101. Taipei 101 was the tallest building until 2010 before Burj Khalifa was built.

The most important building material of Burj Khalifa is reinforced concrete. A special concrete was needed because of the high pressures of the building's weight and the hot local climate of Persian Gulftemperatures that can reach 50 °C (122 °F). Any major cracks could have caused a large amount of damage to the building.

The foundation of the building is 15 metres (49 feet) deep. It was built with 192 columns being put into the ground. Each column was 1.5 metres (4 feet 11 inches) in diameter and 43 metres (141 feet) long.[11] 55,000 tonnes (121,000,000 pounds) of steelrebar was used in the construction of the tower. It took 22 million man-hours to build.[12] A high density, low permeability concrete was used in the foundations of Burj Khalifa. A cathodic protection system is used to lessen any bad effects from corrosivechemicals in local ground water.

A fountain system was built outside the tower. It was designed by WET Design of California. They built and planned out the fountains at the Bellagio Hotel Lake in Las Vegas. The fountain cost UAEd 800 million. It is lit by 6,600 lights and 50 coloured projectors. The fountain is 84 metres (275 feet) long. It shoots water 46 metres (150 feet) into the air to the sounds of classical and modern Arabic and world music.[13] On 26 October 2008, the fountain was named the Dubai Fountain.[14]

Emaar Properties said on 9 June 2008 that construction of Burj Khalifa was slowed because of changes to finishes. An Emaar official said that the luxury finishes that were decided on in 2004, when the tower was first planned, were being being replaced by better finishes. The design of the apartments were also made better. This was done to make them both look better and work better.[15] There were problems with the marbledecorations, flooring, the top floors' sanitation system, broken glasswork and a poorly done wall mural of the Sultan of Oman. A new ending date of 2 December, 2009, was then given.[16] Burj Khalifa opened on 4 January 2010.[17][18]

On 21 March 2006, about 2,500 workers protested. They were mad about buses that were delayed for the end of their shifts. They damaged cars, offices, computers, and construction equipment.[19] A Dubai Interior Ministry official said they caused almost UK£500,000 in damage.[19] Most of the workers who were part of the riot returned the following day but would not work.[19]